Meet the Parkers. They’re a devout, tight-knit family living in the Catskill Mountains – that popular playground for rural American horror on a tight budget. The mother, whose expression of existential nausea in a local shop provides the first note, doesn’t last long in We Are What We Are. But the rest of her clan – bearded patriarch Frank (Bill Sage), his two daughters (Julia Garner and Ambyr Childers) and the youngest, Rory (Jack Gore) – seem undone by more than grief. They look pale and wasted from fierce, ravening hunger. It may have been some months since they last broke fast.

This film, which is neither about vampires nor zombies, but a dire, unvoiced mortal condition, is derived from a 2010 Mexican chiller with the same name: Somos lo que hay. The director is Jim Mickle, who made the fine apocalyptic vampire movie Stake Land (2010), and has a gift for infusing Americana with a folksy dread. His film is no nailbiter – it’s a little too languid and oblique, especially up front – but it has a rare mournfulness in a genre usually obsessed with peekaboo shocks and bloody excess. Taking a softly-softly approach, it divulges the Parkers’ unusual eating habits with something curiously close to tact.

This is the new and sensitive face of indie horror, in the tradition of Larry Fessenden’s terrific Wendigo (2001) and Sean Durkin’s Martha Marcy May Marlene (2011), which were both shot nearby. Mickle prizes credible characterisation above everything else, and casts extremely good actors, who succeed in making the Parker clan feel both frail and somehow stuck out of time, like freak survivors from the 19th century.

Kelly McGillis, as an unsuspecting neighbour hearing bumps in the night, continues to be a warm, welcome presence in these shoestring contexts. And Mickle also has magnetic Michael Parks – the best thing in Kevin Smith’s Red State – as Doc Barrow, the bereaved town coroner, who has a personal reason for coming to the Parkers’ door. His confrontation with Frank is a classic moment: they’re at opposite ends of the dinner table, with bowls of fresh stew, laced with arsenic on top of their already queasy provenance, sitting between them.

The question Doc asks is the one that’s been bubbling up since the moment a small human bone turned up by the river’s edge. Parks places a slow, aggrieved, and deadly emphasis on its third word. "Did you eat my daughter?".